For payloads sent to webdook urls generated by the Slack Button or in response to Slash Commands, text with @usernames or #channelnames is not linked when displayed in Slack, even with link_names set to 1 in the payload.

examples.sh

# Using an 'Incoming Webhook' url, the link_names directive works and #channel and @user are linked in payload text when displayed in Slack

curl -X POST --data-urlencode 'payload={"link_names": 1, "text": "This references the #general channel and the @hpoydar user using a webhook generated as an *Incoming Webhook* configuration", "attachments": [{"text": "Referencing the #general channel and the @hpoydar user in an attachment"}], "channel": "#demo", "username": "webhook-bot", "icon_emoji": ":large_blue_circle:"}' https://hooks.slack.com/services/INCOMING_WEBHOOK_URL

# Using a webhook url generated from the creation of a Slack Button, the link_names directive does not work and #channel and @user are not linked in payload text when displayed in Slack. Same goes for payloads returned in response to slash commands

curl -X POST --data-urlencode 'payload={"link_names": 1, "text": "This references the #general channel and the @hpoydar user using a webhook generated as from a *Slack Button* configuration", "attachments": [{"text": "Referencing the #general channel and the @hpoydar user in an attachment"}], "channel": "#demo", "username": "slack-button-bot", "icon_emoji": ":large_red_circle:"}' https://hooks.slack.com/services/SLASH_BUTTON_INCOMING_WEBHOOK_OR_SLASH_COMMAND